updated centos init script with latest generic-init logic from same branch; some commands don't work yet and will be fixed in subsequent commits
daemonizing tutorial includes a brief paragraph about centos
better (and prettier) use of service functions
replaced tabs with spaces
generic init script now performs status check by verifying whether pids from pid files are running; also exits with appropriate exit status depending on whether commands succeeded or not
removed unused var CELERYCTL
multiple node support for centos script
minor refactoring and bugfixes
using "kill -0" instead of "ps h"; avoiding "$?" because of "sh -e"; minor refactoring
generic init script: removed bashisms; using ls instead of find
centos init script: using ls instead of find, minor refactoring
renamed centos init script to celeryd
updated centos init config file
Removes left-over print statement
Propagate connection errors occurring in pool callbacks.  Closes #1226 (also depends on celery/billiard@5f6cba7200565d846e3bbffbc89716292f448738
fixed restart bug in centos init script
tests for centos init script
events.State should not modify the event dict.
Tests passing
Updates Changelog for 3.0.16